Table 1. Baseline demographic, medical, and lifestyle characteristics of the Women’s Health Initiative (WHI) cohort.
The table contains the N (%) in each cell unless otherwise noted.
| Variables | Training Set (Northeast, Midwest, West Regions) (N = 119,889) |
Test Set (South Region) (N = 41,919) |
Standardized Difference |
|---|---|---|---|
| Age, mean (SD) | 63.54 (7.21) | 62.37 (7.25) | 0.163 |
| Race/Ethnicity | 0.414 | ||
| American Indian or Alaska Native | 543 (0.5) | 170 (0.4) | |
| Asian or Pacific Islander | 3,933 (3.3) | 257 (0.6) | |
| Non-Hispanic Black | 7,696 (6.4) | 6,922 (16.6) | |
| Hispanic | 3,755 (3.1) | 2,729 (6.5) | |
| Non-Hispanic White | 10,2142 (85.4) | 31,399 (75.1) | |
| Other | 1,507 (1.3) | 342 (0.8) | |
| Incomea | 0.103 | ||
| < $10,000 | 4,572 (4.0) | 2,365 (5.9) | |
| $10-20K | 13,524 (11.7) | 4,975 (12.4) | |
| $20-35K | 27,706 (24.0) | 8,959 (22.4) | |
| $35-50K | 23,157 (20.1) | 7,755 (19.4) | |
| $50-75K | 22,479 (19.5) | 7,469 (18.7) | |
| $75-100K | 10,126 (8.8) | 3,487 (8.7) | |
| $100-150K | 6,935 (6.0) | 2,502 (6.3) | |
| > $150,000 | 3,666 (3.2) | 1,257 (3.1) | |
| Don't know | 3,135 (2.7) | 1,249 (3.1) | |
| Occupationa | 0.070 | ||
| Managerial/professional | 46,499 (42.0) | 16,005 (42.1) | |
| Technical/sales/admin | 33,365 (30.1) | 10,758 (28.3) | |
| Service/labor | 19,832 (17.9) | 6,716 (17.7) | |
| Homemaker only | 10,993 (9.9) | 4,544 (12.0) | |
| Diabetes | 6,824 (5.7) | 2,794 (6.7) | 0.041 |
| Medical history | |||
| High cholesterol | 15,716 (13.9) | 5,819 (14.8) | 0.026 |
| Migraine | 12,642 (11.2) | 4,452 (11.3) | 0.005 |
| Atrial fibrillation | 5,171 (4.4) | 1,899 (4.6) | 0.012 |
| Stroke | 1,558 (1.3) | 607 (1.4) | 0.013 |
| Myocardial infarction | 2,747 (2.3) | 957 (2.3) | <0.001 |
| Gallbladder disease or gallstones | 19,560 (16.4) | 6,627 (16.0) | 0.012 |
| Underactive thyroid | 17,602 (15.6) | 5,479 (14.1) | 0.043 |
| Overactive thyroid | 3,215 (2.9) | 1,040 (2.8) | 0.009 |
| Hypertension | 39,918 (33.5) | 14,353 (34.6) | 0.023 |
| Broke bone | 44,622 (39.2) | 14,682 (36.9) | 0.047 |
| Hip fracture at age 55+ | 619 (0.7) | 215 (0.7) | 0.005 |
| Treated hypertension | 0.029 | ||
| Never hypertensive | 75,241 (66.3) | 25,833 (65.3) | |
| Untreated hypertension | 9,288 (8.2) | 3123 (7.9) | |
| Treated hypertension | 29,041 (25.6) | 10,611 (26.8) | |
| Age at menarche | 0.044 | ||
| < 9 | 1,598 (1.3) | 607 (1.5) | |
| 10 | 6,349 (5.3) | 2,021 (4.8) | |
| 11 | 18,322 (15.3) | 6,467 (15.5) | |
| 12 | 31,052 (26.0) | 10,961 (26.3) | |
| 13 | 34,762 (29.1) | 11,833 (28.4) | |
| 14 | 15,925 (13.3) | 5,527 (13.3) | |
| 15 | 6,564 (5.5) | 2,510 (6.0) | |
| 16 | 3,633 (3.0) | 1,416 (3.4) | |
| > 17 | 1,246 (1.0) | 368 (0.9) | |
| Ever breastfeed | 61,152 (51.5) | 21,053 (51.0) | 0.01 |
| Ovaries removed | 0.082 | ||
| None | 85,234 (72.0) | 28,108 (68.4) | |
| One | 8,257 (7.0) | 3,309 (8.1) | |
| Both | 22,730 (19.2) | 8,825 (21.5) | |
| Unknown number removed | 983 (0.8) | 451 (1.1) | |
| Part of an ovary removed | 1,173 (1.0) | 386 (0.9) | |
| Breast biopsy (yes/no) | 26,579 (23.3) | 10,151 (25.6) | 0.053 |
| Number of pregnancies | 0.108 | ||
| Never pregnant | 11,172 (9.4) | 3,718 (8.9) | |
| 1 | 7,863 (6.6) | 3,439 (8.3) | |
| 2-4 | 69,593 (58.3) | 25,379 (61.0) | |
| 5+ | 30,775 (25.8) | 9,092 (21.8) | |
| Number of term pregnancies | 0.150 | ||
| Never pregnant | 11,172 (9.4) | 3,718 (8.9) | |
| Never had term pregnancy | 2,923 (2.5) | 1,318 (3.2) | |
| 1 | 9,859 (8.3) | 4,346 (10.5) | |
| 2 | 28,883 (24.2) | 11,388 (27.4) | |
| 3 | 28,943 (24.3) | 9,896 (23.8) | |
| 4 | 18,696 (15.7) | 5,861 (14.1) | |
| 5+ | 18,742 (15.7) | 5,017 (12.1) | |
| Age at first birth | 0.168 | ||
| Never pregnant | 11,172 (10.3) | 3,718 (10.0) | |
| Never had term pregnancy | 2,923 (2.7) | 1,318 (3.5) | |
| < 20 | 13,764 (12.7) | 6,789 (18.3) | |
| 20-29 | 71,666 (66.0) | 22,561 (60.7) | |
| 30+ | 9,128 (8.4) | 2,787 (7.5) | |
| Mom alive | 29,324 (24.8) | 11,734 (28.5) | 0.084 |
| Dad alive | 10,193 (8.7) | 4,097 (10.1) | 0.047 |
| Relatives’ medical history | |||
| Myocardial infarction | 59,568 (52.4) | 20,605 (52.4) | <0.001 |
| Broke bone | 44,287 (40.0) | 14,828 (38.6) | 0.029 |
| Number of family members with diabetes | 0.092 | ||
| None | 76,175 (67.1) | 25,145 (64.2) | |
| 1 | 25,987 (22.9) | 9,118 (23.3) | |
| 2 | 7,353 (6.5) | 2,951 (7.5) | |
| 3 | 2,318 (2.0) | 1,134 (2.9) | |
| 4+ | 1,652 (1.5) | 836 (2.1) | |
| Breast cancer (Female) | 21,365 (18.8) | 7,045 (17.9) | 0.023 |
| Colorectal cancer (Female) | 9,584 (8.4) | 3,152 (8.0) | 0.015 |
| Colorectal cancer (Male) | 10,252 (9.1) | 3,149 (8.1) | 0.036 |
| Age mother had myocardial infarction | 0.037 | ||
| No MI | 73,873 (77.4) | 23,717 (75.9) | |
| < 55 | 2,694 (2.8) | 920 (2.9) | |
| 55-64 | 4,491 (4.7) | 1,569 (5.0) | |
| > 65 | 13,591 (14.2) | 4,788 (15.3) | |
| Yes, don't know age | 779 (0.8) | 259 (0.8) | |
| Age father had myocardial infarction | 0.023 | ||
| No myocardial infarction | 64,925 (65.3) | 21,495 (64.4) | |
| < 55 | 7,118 (7.2) | 2,405 (7.2) | |
| 55-64 | 9,779 (9.8) | 3,396 (10.2) | |
| > 65 | 16,558 (16.7) | 5,713 (17.1) | |
| Yes, don't know age | 975 (1.0) | 372 (1.1) | |
| Lactose-free diet | 5,878 (5.0) | 1,955 (4.9) | 0.008 |
| Moderate exercise b | 0.064 | ||
| None | 60,078 (52.9) | 21,970 (55.8) | |
| 1 day/week | 13,079 (11.5) | 4,309 (10.9) | |
| 2 days/week | 13,038 (11.5) | 4,256 (10.8) | |
| 3 days/week | 14,436 (12.7) | 4,885 (12.4) | |
| 4 days/week | 5,091 (4.5) | 1,654 (4.2) | |
| >4 days/week | 7,860 (6.9) | 2,326 (5.9) | |
| MET-hours per week from walking (mean, SD) b | 4.80 (6.07) | 4.34 (5.80) | 0.076 |
| Alcohol intake | 0.305 | ||
| Non-drinker | 10,311 (8.7) | 7,341 (17.7) | |
| Past drinker | 21,391 (18.0) | 8,757 (21.1) | |
| < 1 drink/month | 15,201 (12.8) | 4,725 (11.4) | |
| < 1 drink/week | 25,351 (21.3) | 7,586 (18.3) | |
| 1-6 drinks/week | 32,254 (27.1) | 8,919 (21.5) | |
| 7+ drinks/week | 14,624 (12.3) | 4,124 (9.9) | |
| Years smoking, mean (SD) | 3.68 (1.62) | 3.58 (1.62) | 0.062 |
| Resting pulse, mean (SD), beats per 30s | 34.74 (5.85) | 34.91 (6.59) | 0.027 |
| Height, mean (SD), cm | 161.65 (6.63) | 162.06 (6.73) | 0.060 |
| Weight, mean (SD), kg | 73.34 (16.75) | 74.10 (17.35) | 0.045 |
| BMI, mean (SD), kg/m2 | 27.95 (5.89) | 28.05 (6.08) | 0.018 |
| Waist, mean (SD), cm | 86.59 (13.82) | 86.19 (13.89) | 0.029 |
| Hip, mean (SD), cm | 106.30 (12.22) | 106.78 (12.37) | 0.039 |
| Systolic blood pressure, mean (SD), mmHg | 127.30 (17.57) | 127.62 (18.24) | 0.018 |
| Taking aspirin | 26,466 (22.1) | 8,376 (20.0) | 0.051 |
| Taking statins | 9,007 (7.5) | 3,236 (7.7) | 0.008 |
| General health | 0.117 | ||
| Excellent | 20,617 (17.3) | 6,771 (16.3) | |
| Very good | 49,955 (41.9) | 15,681 (37.8) | |
| Good | 38,635 (32.4) | 14,407 (34.7) | |
| Fair | 9240 (7.7) | 4222 (10.2) | |
| Poor | 840 (0.7) | 392 (0.9) | |
SD = standard deviation, MET = metabolic equivalent of task, BMI = body mass index
a
The socioeconomic variables income and education are provided to compare the women who are in the test and training set. They were not included in the risk prediction models.
b
The physical activity variables included in the risk prediction model were calculated from these variables and other physical activity variables.